JP5410443B2 - Method and system for adjusting the cooling capacity of a cooling system based on a gas expansion process - Google Patents

Description

  The present invention relates to a method and system for adjusting the cooling capacity of a cooling system based on a gas expansion process, as can be seen in the preambles of claims 1 and 25 of the patent.

The cooling process based on gas expansion as a cooling principle is a simple and robust cooling device for cooling a gas or liquid to a very low temperature, such as liquefaction of natural gas into LNG or cryogenic separation of air. Often used when required. The gas expansion process is generally based on the classic Brayton / Claude cooling process, in which the gas cooling medium performs a work cycle based on compression, cooling expansion and subsequent heat exchange for the fluid to be cooled. It passes. For example, for liquefaction of natural gas, a pre-cooled and compressed gas phase cooling medium, typically nitrogen or carbon nitride gas, or a mixture comprising a turbine (eg a radial turbine / turbo expander) or an expansion valve A cooling medium that has been pre-cooled and expanded across can be utilized. The expansion of the gas leads to a very cold gas, or a mixture of gas and liquid, which is then utilized to liquefy natural gas and precool the compressed cooling gas . Process is a single expansion loop, or a two or more stage of inflation than be based on the concatenated stages in parallel or in series. In this case, different expansion processes operate at different process conditions (pressure, temperature, flow rate) to increase the efficiency of the process. However, common in most processes is that the cooling medium exists predominantly in the gas phase throughout the entire process.

  Since the cooling medium is predominantly present in the gas phase in the gas expansion process, adjusting the capacity of these processes is often laborious. Capacity adjustment is appropriate when there is little cooling work required to perform the desired cooling and / or liquefaction. For example, when the fluid to be cooled or condensed hardly flows through the system, or when the fluid to be cooled or liquefied is reconfigured to reduce specific cooling work. The reduced capacity is, to a limited extent, by reducing the efficiency of the cooling medium compressor, for example, by variable inlet guide vanes, or by speed control, or by recycling the gas from exhaust to return to the suction of the compressor. Can be realized. However, by reducing the volumetric flow rate of the coolant, the expansion turbine also provides reduced efficiency and low power output, and more importantly, problems with expansion turbine control arise, or The expansion turbine cannot be operated when time has elapsed in such an operating range. In that case, a situation may arise where the desired low temperature required for the process cannot be achieved.

  Other principles are commonly used as a result of equipment-related limitations for reducing cooling capacity in the process. In this case, the capacity of the cooling medium in the closed cooling circuit is reduced (removed permanently or temporarily from the closed loop). In this way, the operating pressure in the entire cooling circuit is reduced on both the high pressure side and the low pressure side. Generally, radial compressors and radial turbines are used in such cooling processes. Also, because the compression or expansion in these machines is based on volume, the facility continues to handle a relatively constant real volume per unit time. By reducing the operating pressure, the same real volume flow is circulated, but the weight flow is lower. In this way, a low cooling efficiency is achieved with a corresponding reduction in the required compression work. On the other hand, the system operates near its design point.

  The problem with the latter method for capacity adjustment is the loss of cooling gas in the case of a temporary reduction in cooling capacity. In large equipment, after a period of capacity reduction, it is necessary to spend a very long time to supply a large amount of appropriately quality cooling gas, for example purified nitrogen. Therefore, it takes a long time to restore the ability. An alternative to gas storage or trapping between the two pressure levels at which the process operates is used, and that alternative constitutes a reasonable alternative for small devices. Other solutions have a reservoir of cooling medium gas in the pressure vessel, so that a large amount of gas can be injected into the cooling circuit when additional quantities are needed.

  The present invention represents a significant optimization in capacity adjustment for gas expansion circuits, in particular large devices such as cooling devices for the production of LNG. Here, the cooling process is modified as follows. That is, the cooling medium gas is simply cooled for intermediate storage in liquid form and liquefied in a relatively short time. In this way, the cooling medium gas is temporarily removed from the cooling circuit. The cooling circuit then operates at a lower fill rate at subsequent lower operating pressures and reduced cooling efficiency. The liquefied gas can be re-evaporated into the cooling circuit at any time to quickly increase the efficiency of the cooling device. Storage of coolant gas at low temperatures in liquid form will require a significantly smaller storage volume than storage of gas in compressed form. If the efficiency of the device is reduced and there is a surplus of cooling capacity in the device, the liquefaction of the cooling medium gas does not require a large cooling capacity in the cooling device because liquefaction is performed in a short period of time.

  The present invention relates to all types of nitrogen expansion cycles, or a gas expansion cycle using a mixture of pure methane, natural gas or hydrocarbons, where the cooling medium is dominant in the gas phase throughout the entire cooling circuit. Are intended for use in all types of gas expansion circuits. Here, the cooling is obtained by expanding the gas cooling medium.

Means for Solving the Invention

The above-mentioned problem is a method for controlling the cooling capacity of a cooling system using a cooling circuit for expansion cooling of a gas, as described in the independent claim 1, comprising:
Temporarily reducing the amount of cooling medium circulated in the cooling circuit, wherein a portion of the cooling medium is precooled at a higher pressure and removed from the cooling circuit;
Expanding the cooled portion of the cooling medium in the gas phase or liquid phase across the expansion device to a lower pressure, thereby separating at least a portion of the cooling medium as a cold liquid; ,
Separating condensed liquid from non-condensed gas for temporary storage in a storage unit, whereby the liquid is temporarily not circulated in an otherwise closed cooling circuit;
Thereafter, when necessary, returning the temporarily stored liquid phase cooling medium from the storage unit to the cooling circuit;
Returning the uncondensed gas and the evaporated cooling medium from the storage unit to a suitable place in the cooling circuit;
It is realized by the method consisting of

  Preferred forms of the method are described in the dependent claims 2-23.

The above-mentioned problem is a system for capacity reduction in a cooling system based on gas expansion cooling, as described in independent claim 24, comprising:
A device for cooling a gas cooling medium at a higher pressure in a heat exchanger or heat exchanger system with support of a cooling process;
An outlet for a tributary of a cooling medium cooled in the gas phase or liquid phase;
An expansion device for expanding the tributary into a flow at a lower pressure;
A reservoir for separation of the uncondensed cooling medium and temporary storage of the condensed cooling medium;
A return device for returning the uncondensed coolant gas and the evaporated coolant from the storage unit to the appropriate location in the cooling system;
A return device for returning the cooling medium from the storage unit to the cooling circuit when needed,
Realized by a system provided to temporarily remove the cooling medium from the closed cooling circuit or cooling circuits.

  Preferred forms of the method are evident in the dependent claims 26 and 27.

FIG. 1 shows the main operating principle of the present invention. FIG. 2 shows the main operating principle of the present invention in another form. FIG. 3 shows the main operating principle of the present invention in another form. FIG. 4 shows the main operating principle of the present invention in another form. FIG. 5 shows the main operating principle of the present invention in another form. FIG. 6 illustrates the present invention for a simple gas expansion circuit. FIG. 7 shows the invention for a simple gas expansion circuit in another form. FIG. 8 illustrates the present invention for a simple gas expansion circuit in another form. FIG. 9 illustrates the present invention for a simple gas expansion circuit in another form. FIG. 10 shows the invention for a simple gas expansion circuit in another form. FIG. 11 shows the invention for a simple gas expansion circuit in another form. FIG. 12 shows the present invention in a preferred form for a two-stage gas expansion circuit.

Referring to FIGS. 1 and 2, the system for controlling the capacity of the gas expansion circuit includes the following main components.
1. 1. Cooling of the part of the cooling medium at a higher pressure by the cooling process 100 Removal of the cooled portion of the cooling medium for expansion to a lower pressure across the pressure reducing device 102; Thereby, at least a small part of the cooling medium in the cooling medium flow 13 is liquefied at a low pressure.
3. Reservoir / tank 104 for liquid phase coolant
4). Separation of the cooling medium stream 13 into a stream consisting of uncondensed cooling medium gas 14 and liquid phase cooling medium. Preferably, this separation occurs in the cooling medium tank 104.
5. Return of uncondensed and evaporated coolant from tank 104 to the appropriate location in cooling system 100.
6). A device 106 for returning the cooling medium from the storage tank 104 to the cooling circuit 100 as needed due to increased load.

  Cooling of the cooling medium at a higher pressure is generally cooling to a temperature lower than the lowest precooling temperature of the cooling medium in the main cooling circuit. That is, the coolant flow to be drawn for expansion to a lower pressure across the pressure reduction device 102 is generally more pre-cooled than other coolant flow during the normal mode of operation for the cooling circuit. It needs to be further cooled. However, the precooling temperature for the coolant stream drawn for expansion to a lower pressure across the pressure reducing device 102 cannot be cooled to a temperature below the lowest operating temperature at the cooling temperature, The cooling medium is typically a return cooling medium stream that is expanded from a higher pressure to a lower pressure, as shown, for example, as flow 32 in FIG. In this case, the cooling system uses one or more multi-stream heat exchangers, such as a multi-stream plate-fin heat exchanger, and the cooling is, in part, Occurs in part as part of the precooling path 190 of the main cooling circuit. That is, it occurs partially as a dedicated extension 191a in this pre-cooling pass. FIG. 1 shows this configuration as if the pre-cooling path 190 of the cooling circuit was extended directly in the form of a heat exchanger path 191a. On the other hand, the cooling medium flow 31 of the main cooling circuit is extracted from the heat exchanger 110a at an intermediate outlet in the heat exchanger. FIG. 2 shows another form in which the cooling medium is first cooled in the pre-cooling path 190 of the cooling circuit and is removed from the heat exchanger 110a as stream 31 and is multi-staged for further cooling in the heat exchanger path 191b. The form returned to the stream heat exchanger 110a is shown.

  FIG. 3 shows other forms of some further principles that can be used individually or simultaneously. FIG. 3 shows another configuration, in which one or more of the multi-stream heat exchangers in the heat exchanger system is used to cool part of the gas cooling medium in a separate pre-cooling path 191c. A fully implemented embodiment is shown. Cooling may also occur in individual heat exchangers with the assistance of the cooling system 100. In addition, FIG. 3 shows a configuration in which the coolant reservoir 104 is operated at a pressure higher than the receiving pressure for coolant return. Here, the pressure control valve controls the pressure at 104 by limiting the return of the gas flow to the cooling circuit. FIG. 3 also shows that the cooling medium 12 is returned by heating in the individual paths 192 of the heat exchanger 110a. If a system 110b (FIG. 5) consisting of multiple heat exchangers is used in the cooling circuit, a corresponding configuration can also be used.

  FIG. 4 illustrates two other forms that may be used together or individually or in conjunction with any of the forms described above and in FIGS. In FIG. 4, the non-condensed portion of the cooling medium 14 is not returned to the cooling system, but from the otherwise closed cooling system, as stream 14b, for example, to the atmosphere or other in the process plant. Guided for use on site. FIG. 4 also illustrates one form in which the system can supply nitrogen to the other parts of the processing apparatus as a stream 145 in liquid or gaseous form.

  FIG. 5 is one other form in which the cooling process uses multiple multi-stream heat exchangers as the heat exchanger system 110b and the cooling medium is initially in the pre-cooling path 190 of the cooling circuit. The configuration is shown being cooled and taken as stream 31 from one of the heat exchangers in system 110b. The tributary 11a is withdrawn from stream 31 and returned to the system 110b for further cooling in the heat exchanger path 191a in the subsequent heat exchanger.

  FIG. 6 shows in detail the present invention used in a simple gas expansion circuit, such as a simple nitrogen expander cooling circuit. It has been shown that the present invention can also be used with other types of gas expansion circuits using various types of cooling media and one or more expansion stages. The cooling process begins at a higher pressure in the gas stream of the cooling medium 21 that has been pre-cooled in path 190 in the multi-stream heat exchanger 110. This allows the precooled coolant 31 to be expanded across the gas expander 121 to produce a cold coolant stream 32 at a lower pressure. Although the flow of the cooling medium 32 is predominantly in the gas phase, in some designs, a small portion of the liquid may be allowed to equilibrate with the gas at the expander / turbine outlet. The low-temperature cooling medium 32 is returned to the heat exchanger 110. The cold coolant 32 also provides the cooled product 7 of the process to cool the hot coolant stream 21 in the coolant path 190 and the process fluid 1 in one or more coolant paths 193. Cooling and / or liquefaction of After heating at 110, the cooling medium stream exits as a gas at the low pressure of stream 51. This cooling medium stream is compressed again in one or more compression stages 111 with or without intermediate cooling. The compressed cooling medium 20 is then finally cooled using an external cooling medium or an external cooling circuit 130. In this situation, the present invention further draws the coolant stream 191a at a higher pressure after precooling in the heat exchanger 190 until the cold coolant stream 12a is formed at a higher pressure to precool at 191a. Begins with. The pre-cooled cooling medium 12a can be in a gaseous or liquid state and is then expanded across the valve 102 to a lower pressure or between a higher pressure and a lower pressure. However, this reduces the temperature and produces a mixture of gas 13 and at least a portion of the liquid. Valve 102 will also reduce the amount of cooling medium drawn from the cooling circuit in this situation. Gases and liquids in stream 13 can be stored in a storage tank / pressure tank / separator 104 at a suitable pressure and in a suitable location in the cooling circuit, eg, stream 32 as shown in FIG. And the gas stream 14 returned to When the system described above draws the cooling medium through path 191a and valve 102 and liquid is produced at 104, the capacity of the cooling medium in the cooling circuit is correspondingly reduced and the capacity of the cooling device is also reduced. Is reduced. When the capacity is to be increased again, a suitable device 106 moves the cooling medium from the tank 104 to the cooling circuit, preferably to the part of the cooling circuit having a lower pressure, for example to the cold side 32 at the lower pressure. As a stream 17a or as a stream 17b to the hot side 51 at a lower pressure.

  The device 106 for return and control of the coolant to the cooling circuit when increased capacity is required, in its simplest form, is a valve or pump for injecting fluid into the cooling circuit. There may be. With regard to the use of the valve, the flow of fluid back to one of the parts of the cooling circuit, the flow operating at lower pressure, is due to gravity flow as a result of the height difference or FIG. 3 and the associated description. Can be generated by a reservoir 104 operating at a higher pressure, as described in.

  With respect to the use of the pump in the device 106, it is also possible to return the cooling medium to the part of the cooling circuit that operates at higher pressures or the part that operates at intermediate pressures.

  FIG. 7 is the present invention applied in a simple gas expansion circuit having other configurations for returning the cooling medium from the reservoir 104 to the cooling circuit, for supplying heat to the cryogenic liquid cooling medium at 104. 1 shows the present invention with the device 107 used. In this way, the liquid cooling medium at 104 is evaporated in a controlled path back to the cooling circuit via the gas line 14.

FIG. 8 illustrates the present invention used in a simple gas expansion circuit having other configurations for returning the cooling medium from the reservoir 104 to the cooling circuit. Here, a device 142 external to the tank 104 is used to supply heat to the cryogenic liquid cooling medium. Also, in this way, the liquid cooling medium from 104 is evaporated in a controlled path that returns to the cooling circuit via the gas lines 17a, 17b or corresponding connections. Device 143 may be, for example, a heat exchanger that uses ambient air as a heat source, or may be another type of heat exchanger that has a hot medium available as an energy source.

  FIG. 9 illustrates the present invention used in a simple gas expansion circuit having other configurations for returning the cooling medium from the reservoir 104 to the cooling circuit. Here, an ejector / discharger 108 is used to obtain a controlled flow of cooling medium back to the appropriate location in the cooling circuit. The exhaust 108 uses a limited amount of inductive gas 18 from the high pressure side of the cooling circuit, for example from the compressor outlet 20 or from the cooling medium stream 21 downstream of the cooler 130. The cooling medium can be returned to the portion of the cooling circuit having a lower pressure, for example, as a flow 17a to the cold side 32 at a lower pressure or as a flow 17b to the hot side 51 at a lower pressure. The evacuator provides complete or partial evaporation of the cryogenic liquid 16 so that the return cooling medium 17a / 17b is no longer pure, with subsequent dangers in the cooling circuit during the period of return of the cooling medium. An undesirable liquid / gas stream of cryogenic liquid is carried away.

  FIG. 10 shows the present invention applied in a simple gas expansion circuit having other configurations for returning the cooling medium from the reservoir 104 to the cooling circuit, wherein an external volume 143, such as a container or pipe, The present invention is preferably used in the vertical direction. Here, the flow of the liquid cooling medium 16 is guided to the volume part in a controlled path. Also, the flow of the liquid cooling medium 16 is a high temperature gas 18 from a high pressure side of the cooling circuit, such as a high temperature from the outlet 20 of the compressor or from the cooling medium stream 21 downstream of the cooler 130. Mixed with gas 18. The hot gas 18 is then allowed to evaporate the desired amount of cooling medium into a gas and, for example, as a flow 17a to the cold side 32 at a lower pressure or to the hot side 51 at a lower pressure. Heat is supplied as stream 17b so that it can be returned to the part of the cooling circuit having the lowest pressure. This configuration leads to complete evaporation of the cryogenic liquid 16, whereby the return cooling medium 17a / 17b is no longer cold with the subsequent danger of undesirable liquid / gas in the cooling circuit while the return of the cooling medium is carried away. It is no longer liquid.

  FIG. 11 shows the present invention applied in a simple gas expansion circuit having other configurations for returning the cooling medium from the reservoir 104 to the cooling circuit, which is introduced into the 104 via a suitable device, such as a nozzle. FIG. 6 illustrates the present invention with the apparatus used when a high temperature coolant stream 18 is supplied from a location in the cooling circuit where the pressure is somewhat higher than in the reservoir 104. Thereby, the heat in the hot gas contributes to the controlled evaporation of the cold liquid at 104. In this way, the liquid cooling medium at 104 is evaporated back into the cooling circuit via the gas line 14 in a controlled path.

  For example, cooling systems for LNG liquefaction are often more comprehensive / include more detailed than those addressed by the above description. However, the principle for the form of the invention is the same. To illustrate this, a cooling system for liquefaction of natural gas to LNG is shown in FIG. 12 by utilizing a two-phase gas expansion circuit using pure nitrogen as the cooling medium. The gas stream 1 containing the natural gas to be liquefied is cooled by the heat exchanger 110 in more than one stage. Here, the gas is pre-cooled to a predetermined intermediate temperature 4 where heavier hydrocarbons can be separated as a liquid in a separator or column 160. The precooled gas 6 is then returned to the heat exchanger 110 for further cooling, condensation and subcooling until liquid is present as LNG in the product stream 7. The cooling circuit now includes a gas coolant stream 21 at a higher pressure divided into two parts 30 and 40 that have been precooled to different temperatures in the heat exchanger 110. Stream 30 is pre-cooled to a temperature below that at 30 and is expanded across gas expander 121 to produce a cold coolant stream 32 at a lower pressure. The coolant stream 32 is predominantly in the gas phase, however, in some designs, a small liquid portion that is in equilibrium with the gas at the expander / turbine outlet may be allowed. The low-temperature cooling medium 32 is returned to the heat exchanger 110 so as to contribute to cooling. Stream 40 is pre-cooled to a temperature below that at 32 and is expanded across gas expander 122 to produce a cold coolant stream 42 at a lower pressure. The coolant stream 42 is predominantly in the gas phase, however, in some designs, a small liquid portion that is in equilibrium with the gas at the expander / turbine outlet may be allowed. The cryogenic cooling medium 42 is returned to the heat exchanger 110 to ensure cooling in the lowest temperature range. After warming up at 110, the coolant stream is now present as gas streams 33 and 43 at a lower pressure. These gas streams can then be compressed again with or without intermediate cooling in two or more compression stages. It should be pointed out that the separation of the coolant flow does not necessarily have to occur before the heat exchanger 110, but may occur as an integrated part of the heat exchanger 110. In this case, the pass splits the gas flow for the discharge of the stream 31 at the intermediate outlet and for further cooling of the remaining gas 41. Similarly, heating of the cold gases 32 and 42 can occur in such a way that the streams are mixed as an integrated part of the exchanger. As in the case of a simple gas expansion circuit, the form of the present invention is the heat exchanger path in this situation until the cold coolant stream 12a is present at higher pressures for further precooling at 191a. Begin by drawing the coolant stream 191a at a higher pressure after pre-cooling at 190. It should be pointed out that all of the methods for the separation of the cooling medium tributaries for further cooling described above and in FIGS. 1 to 3 can also be used in this configuration. The pre-cooled cooling medium 12 is expanded across the valve 102 to a lower pressure, or to a pressure between higher and lower pressures, thereby reducing the temperature and gas And a mixture of at least a portion of the liquid is produced. In this relationship, the valve 102 controls the amount of cooling medium drawn from the cooling circuit. Gases and liquids in stream 13 are separated into a portion of the liquid that can be stored in storage tank / pressure tank / separator 104 at the appropriate pressure and a lower pressure gas stream 14 that is returned to the appropriate location in the cooling circuit. Is done. For example, it is separated into streams 32 or 42 via 14b and 14a, respectively. When the system described above draws the cooling medium through path 191a and valve 102 and liquid is generated at 104, the capacity of the cooling medium in the cooling circuit is correspondingly reduced and the capacity of the cooling device is also reduced. Is reduced. When the capacity is to be increased again, the flow 16a from the cooling medium 16 to the cooling circuit, preferably to the part of the cooling circuit having a lower pressure, e.g. to the cold side 32 at a lower pressure, or A suitable device 106 is used to return as stream 17c to the cold side 42 at lower pressure or as stream 17b to the hot side 51 at lower pressure. All the alternative methods described above for returning the cooling medium to the cooling circuit can also be used.

  In all configurations of the present invention, the gas stream 14 can be returned to a location other than the location of the cooling circuit described by the above figures and examples, as long as the pressure is sufficiently low, and the present invention It should be pointed out that it is not limited to the examples described here.

  In all forms of the invention, with respect to the method used for return, the cooling medium 17 is returned to a location other than the location of the cooling circuit described by the above figures and examples as long as the pressure is sufficiently low. It should be pointed out that, and the invention is not limited to the examples described herein.

  In all forms of the invention described in the above description and figures, the cooling medium tank may be configured as a horizontal tank or a vertical tank. Further, the cooling medium tank 104 may be a conventional tank or a tank that is double walled and insulated with a vacuum, commonly used to store cryogen / cold liquid and liquid gas. There may be.

  Further, the cooling medium tank 104 may be located in the vicinity of the cooling system 100 and the heat exchanger system 110, and the cooling medium tank 104 is insulated to minimize evaporation as a result of heat transfer from the surroundings. It may be. In other forms, the cooling medium tank 104 may be filled with an insulating material to limit heat transfer from the surroundings, closed, or disposed with the heat exchanger 110 inside a limited volume. . Insulated volumes are often shaped as boxes and are generally represented as “cold boxes”. The insulating material may be a conventional insulator or may be a granular insulating material that is filled into the box.

  In other forms, the cooling medium tank 104 can also be used as a cooling medium reservoir, for example when the cooling medium is nitrogen. This allows the cooling medium tank to supply other parts of the processing device with liquid or gaseous nitrogen when needed.

Claims (26)

In a method for controlling the cooling capacity of a cooling system using a cooling circuit (100) constituted by cooling obtained by expanding a gaseous cooling medium ,
Comprising the steps of temporarily reducing the amount of coolant circulating in the cooling circuit (100), one part of the total cooling medium, while being pre-cooled at a higher pressure, it is extracted from the cooling circuit (100) Process,
The extracted portion of the cooled the cooling medium is lower than the high pressure is passed through a pressure reduction device (102), it is expanded to a lower pressure, whereby at least some amount of the extracted cooling medium The process of liquefying,
Separating the liquid phase cooling medium from uncondensed cooling medium gas for temporary storage in a storage unit (104);
Then returning the temporarily stored liquid phase cooling medium from the storage unit (104) to the cooling circuit (100) when necessary;
Returning the uncondensed cooling medium gas and the evaporated cooling medium from the storage unit (104) to the cooling circuit (100 ) . First portion of the cooling medium in the high pressure, according to claim 1, wherein the benzalkonium precooled to a temperature lower than the temperature at which other cooling medium flow is pre-cooled at a higher pressure in the cooling circuit Method. First portion of the cooling medium in the high pressure, such that at least a portion of the first portion of the cooling medium after the pre-cooling is present as a liquid, or, as the whole of the cooling medium after the pre-cooling is present as a liquid, a predetermined The method of claim 1 , wherein the method is precooled to a temperature of First portion of the cooling medium in the high pressure, so as to present as a cooling medium one part is still gas in the cooling medium after the pre-cooling, according to claim 1, characterized in that it is pre-cooled to a predetermined temperature Method. The method of claim 1 , wherein the pressure reducing device (102) for expanding a pre-cooled cooling medium from a high pressure to a low pressure comprises a valve . Cooling system, expansion cooling circuit of the gas (100) is used, it is used for the production of liquid natural gas (LNG), wherein cooling is to ensure cooling and liquefaction of natural gas, cooling the gas Obtained by expanding the medium ,
In the cooling circuit (100), the capacity is controlled,
The amount of cooling medium circulated in the cooling circuit is temporarily reduced,
First portion of the cooling medium gas is inflated to a lower pressure than the high pressure passes through the bulging Zhang devices together when it is pre-cooled at a high pressure (102), whereby, at least a portion of the cooling medium Separated as a cryogenic liquid,
The solution is to be returned to the cooling circuit after, for temporary storage in savings built unit (104), The method according to claim 1, characterized in that it is separated from the gas which is not condensed. The cooling circuit (100) consists of a gas expansion cooling circuit using a cooling medium composed of more than 90% nitrogen,
The cooling circuit (100) comprises at least one expansion stage, wherein the precooled gaseous cooling medium is expanded from a high pressure to a low pressure to produce a cold gaseous cooling medium. The method according to claim 1 or 6 . A storage unit (104) for temporarily storing the cooling medium separates the uncondensed cooling medium from the liquid phase cooling medium in the cooled and expanded cooling medium stream (13) drawn from the cooling system. The method of claim 1 , wherein the method also functions as a separation unit. The storage unit (104) is operated at approximately the same pressure as the low pressure in the cooling circuit,
8. A method according to claim 7 , characterized in that the storage unit (104) has an unrestricted connection (14) to the part of the cooling circuit operated at low pressure. The storage unit (104) is operated at a pressure between high and low pressure in the cooling circuit,
8. Method according to claim 7 , characterized in that the storage unit (104) has a connection (14) provided with a restriction consisting of a valve for the control of the operating pressure in the storage unit. 2. Method according to claim 1 , characterized in that a storage unit (104) is used, comprising a pressure tank with or without insulation, or a double walled, vacuum-insulated pressure tank. . The method according to claim 1 , characterized in that the cooling medium stored in the storage tank (104) is returned by the return device (106) to the part of the cooling circuit (100) which is operated at low pressure. Apparatus for returning the cooling medium (106) in claim 1 or 12, characterized in that it comprises that the one, or more valves directing cooling medium in the liquid phase back to the cooling circuit (100) The method described. Apparatus for returning the cooling medium (106) to supply heat to the stored liquid in the storage unit (104), or, supplying heat to the outside connected heat transfer equipment storage unit (104) Ready to
13. A method according to claim 1 or 12 , characterized in that this realizes a controlled evaporation of the stored liquid with respect to the return of the cooling medium in the gas phase. 13. A method according to claim 1 or 12 , wherein the apparatus (106) for returning the cooling medium comprises using a pump to return the cooling medium to the cooling circuit (100). The apparatus (106) for returning the cooling medium comprises using an ejector / discharger for returning the cooling medium to the cooling circuit (100 ) by a controlled path,
13. A method according to claim 1 or 12 , characterized in that the discharger / discharger uses an induced gas from the high pressure side of the cooling circuit. The apparatus (106) for returning the cooling medium comprises using a volume consisting of a pipe or a pressure vessel,
The cooling medium to be returned from the storage tank (104) to the cooling circuit (100) is led to the volume by a controlled path,
Furthermore, the hot gas stream from the cooling circuit is supplied to the same volume part,
Claim Thereby, the hot gases, and supplying the energy required to return the cooling medium evaporated with evaporating a sufficient amount of the cooling medium from said volume from the volume to the cooling circuits The method according to 1 or 12 . 18. A method as claimed in any preceding claim , wherein the gas expansion cooling circuit comprises one or more gas expansion stages in parallel or in series. All or part of the system comprises an expansion device ( 102 ) , a storage tank ( 104 ) and a system for return of cooling medium ( 106 ), which are filled with an insulating material, often represented as a “cold box” 19. A method according to any of the preceding claims , characterized in that it is arranged with a heat exchanger system ( 110 ) in a closed or confined volume. The uncondensed gas and the evaporated cooling medium from the storage unit (104) are not returned to the cooling circuit (100), but instead are used in a given system or a system external to the closed cooling circuit. The method according to claim 1 , wherein the method is released to the atmosphere / ambient. The system is for controlling the capacity of a cooling cycle using nitrogen as a cooling medium, and the system supplies gas phase or liquid phase nitrogen to a predetermined system or external to a closed cooling circuit. the method of claim 7, wherein the luck BUKO system. In a system for controlling the cooling capacity of a cooling device based on gas expansion cooling,
A cooling device for cooling a gaseous cooling medium at high pressure with the aid of a cooling process in a system consisting of a heat exchanger (110a) or a heat exchanger (110b);
A discharge unit for the portion of the cooling medium cooled gas,
An expansion device (102) for causing bulging Zhang a portion of the cooling medium to a lower pressure than the higher pressure than the said gas,
A storage unit (104) for separation of the uncondensed cooling medium and temporary storage of the condensed cooling medium;
A return device for returning the uncondensed coolant gas (14) and the evaporated coolant from the storage unit (104) to the cooling system (100 ) ;
A return device (106) for returning the cooling medium from the storage unit (104) to the cooling circuit (100) as needed,
A system characterized in that the cooling medium is provided to be temporarily removed from the closed cooling circuit or circuits. The cooling circuit (100) comprises a multi-stream heat exchanger (110a) or a heat exchanger system comprising a number of multi-stream heat exchangers arranged in the heat exchanger system (110b),
The heat exchanger system is configured to perform pre-cooling of one or more cooling medium streams at a higher pressure in the heat exchanger path so that the portion of the cooling medium can be pre-cooled. After the precooling of the coolant stream at a higher pressure at (190), the precooled coolant (31) for the coolant circuit (100) is removed from the heat exchanger system, Characterized in that it is extracted from the path of the heat exchanger at the discharge and the part of the cooling medium is arranged to be further cooled in the extension (191a) of the pre-cooling path (190) of the heat exchanger. The system of claim 22. The cooling circuit (100) comprises a multi-stream heat exchanger (110a) or a heat exchanger system comprising a number of multi-stream heat exchangers arranged in the heat exchanger system (110b),
The heat exchanger system is configured to perform pre-cooling of one or more coolant streams at higher pressures in the heat exchanger path;
At least one coolant stream (31) was pre-cooled at a higher pressure in the heat exchanger path (190) and extracted from the heat exchanger system, whereby the portion of the coolant was pre-cooled. 23. Method according to claim 22, characterized in that it is separated from the cooling medium stream (31) and returned to the heat exchanger system for further precooling in a separate heat exchanger path (191b). The cooling circuit (100) comprises a multi-stream heat exchanger (110a) or a number of multi-stream heat exchangers arranged in a heat exchanger system (110b), which are connected to the cooling system ( 100) and the cooling or heating of the fluid to be cooled or liquefied, whereby the cooling of said part of the gaseous cooling medium is one of the heat exchanger systems. 25. A method as claimed in any of claims 22 to 24, occurring in separate precooling passes (192) of the multi-stream heat exchanger or more. The closed gas expansion circuit consists of a gas expansion circuit using pure nitrogen as the cooling medium, and the high pressure gaseous cooling medium stream is at different temperatures in the heat exchanger or heat exchanger (110) system. Divided into two parts to be pre-cooled, and further, the two cooling medium streams are cooled to different temperatures and passed through different expansion devices to form two cooling medium streams of different temperatures. Expanded to one or more lower pressures,
The cooled gaseous coolant tributary (12) to be further cooled for expansion through the expansion device (102) is pre-cooled to the lowest temperature of the two above-mentioned partial streams. The cooling medium is drawn from a precooled partial stream, and the discharge occurs at a high pressure before the precooled partial stream is expanded to a low pressure and temperature;
The expansion device (102) for expanding the tributary (12) into the flow (13) at low pressure consists of a valve,
Of the gaseous cooling medium that has passed through the expansion device (102), the portion of the non-condensed cooling gas and the cooling medium evaporated from the storage tank (104) are directed to the cooling circuit (100 ) ,
A return device (106) for returning the cooling medium from the storage unit (104) to the cooling circuit (100) comprises a volume consisting of a pipe or a pressure vessel and is returned from the storage tank (104) to the cooling circuit (100). The cooling medium to be supplied is led to the volume part through a valve by a controlled path, and the hot gas flow is supplied from a cooling circuit having a pressure higher than that of the storage unit, and further evaporated from the volume part. the system of claim 25, the cooling medium, characterized in that the back cold 却回path.

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